Conventionally a device for internal deburring of welded tubes is positioned within the tube and remains stationary as the conduit or tube is continuously formed and is propelled over the deburring device. A cutting or deburring blade or surface mounted on the device contacts and removes the tube weld or burr.
The cutting or deburring blade is typically a cutting ring angularly mounted on a trailing head portion of the deburring device to contact the inwardly projecting burr.
Prior known cutting rings such as those described in U.S. Pat. No. 4,710,078 are shaped and positioned in the head of a deburring device so that the cutting edge effects a cutting-scraping action to remove the burr. Such action effects a notch where the burr is removed that narrows the gauge of the metal and weakens the structure. The "notch effect" is caused primarily by the fact that the cutting ring is of lesser diameter than the tubing so that the arc of the cut is of lessor radius than the arc of the tube. As a result of the lessor radius of the ring, the cut encroaches on the gauge of the tube.
Additionally, the scraping action produces particles of metal and weld scale in quantities that do not clear the device through the ring and openings in the head effectively. Consequently the particles find their way into the moving and adjustable parts of the device and cause wear thereby reducing their effective time of operation.
Prior known devices that effectively cut the weld rather than the cutting-scraping action such as that shown by U.S. Pat. No. 4,138,925 also cause a notch effect and additionally are formed with a passage way through which the weld burr must pass that is too long to effectively allow such burr and particles to pass and clear the device and thus have proved to be ineffective.
Prior known devices such as those shown and described in U.S. Pat. Nos. 4,710,078 and 4,138,925 are subject to penetration of particles from the deburring operation into their mechanisms for positioning the cutting rings relative to the seam or weld. Such devices also are provided with guide and pressure wheels which ride on the inside surfaces of the tubes and space the devices for cutting. Spring mechanisms designed to maintain the positioning of such devices within the tubes must be adjusted outside of the tubes and typically fracture and fail when subject to contact with obstacles (dirt, weld, particles) typically found in such tubes during deburring.